Abstract: The technology of coal hydrogasification to natural gas has the advantages of short process and high thermal efficiency.The basic research of its application has attracted much attention.However,coal structure contains large quantities of inert carbon and the hydrogenation reactivity is poor,which are hard to be converted although harsh reaction conditions(～1 000℃,～7 MPa) are applied.The reactivity of coal can be improved by adding desirable catalysts,and The carbon conversion and CH_4 yield under mild conditions can be increased simultaneously by coal catalytic hydrogasification(CCHG).The catalytic mechanism of alkali metal(K,Na,et al.),alkaline earth metal(Ca),and transition metals(Fe,Co,Ni,et al.) on hydrogasification of model carbon was reviewed.The effects of temperature,H_2 pressure and carbon structure on C-H_2 catalytic reaction process were discussed.On these bases,the optimal catalyst and process conditions forthe catalytic hydrogasification of raw coal were proposed.Moreover,the catalytic behavior of catalysts on hydropyrolysis of coal and hydrogasification of pyrolyzed coal char were analyzed,in terms of formation of CH_4 and light hydrocarbon liquids (HCL) and the evolution process of carbon structure in coal with the reaction.Finally,further research suggestions for co-production of CH_4 and HCL from CCHGwere put forward from an application perspective.The existing research results indicate that the use of iron-group metals with calcium salts(Fe/Co/Ni-Ca) as bimetallistic catalysts hasprofound catalytic performance on hydrogasifification.Transition metals mainly provide active hydrogen for C-H_2 reaction and decrease the energy for the fracture of C—C bonds.Ca mainly promotes the dispersion of transition metals and prevents its deactivation by sulfur poisoning,and enhances catalyst-carbon interaction.On the one hand,higher temperature provides higher energy for fracturing chemical bonds in coal,and accelerates the C-H_2 reaction.On the other hand,higher temperature facilitates the diffusion of the catalyst into the interior of coal matrix,and thus promotes the active hydrogen supplying and C—C bonds fracturing efficiency.Increasing pressure promotes the supply of active hydrogen,meanwhile,dilutes the concentration of CH_4,and the reaction moves to the direction of generating CH_4.In the presence of 5%Co-1%Ca at 850℃and 3 MPa,90.0%of coal conversion and 77.3%of CH_4 yield can be simultaneously achieved in 30 min.Co-Ca catalyst has the function of catalytic depolymerization and hydrogenation effect on coal during hydropyrolysis,which resulted in the promoted yield of CH_4,tar.At the same time,the catalyst has the catalytic activation effect on the coal structure in the process of coal hydropyrolysis,which makes the semi coke have higher gasification activity.The mechanism of coal catalytic hydrogenation remains in the speculation stage.In addition,the catalyst recycling performance and adaptability of gasification agent and coal type need to be further clarified.